Wiper arms of this general type are known in many different varieties. For instance, according to FR-A 2 517 609, the connecting head is unrotatably coupled to the drive shaft of the wiper drive which is arranged below the windshield of the automotive vehicle and is oscillated by means of a known mechanism. To be able to lift the wiper from the windshield, the arm head is pivoted at the connecting head about the mentioned mounting axis, which extends roughly perpendicular to the wiper drive shaft. A tension spring is typically employed for urging the wiper blade firmly against the windshield.
In order to ensure the proper contact pressure of the wiper at the windshield and its correct alignment in relation to the windshield surface, the wiper holder must be aligned in relation to the windshield surface, which may be different in various vehicle designs. Ideally the wiper blade should be maintained perpendicular to the windshield surface.
This objective is achieved, for instance, by bending the wiper rod by the necessary angle. When the turning range is short, a bent wiper rod is generally considered to be unattractive and accordingly it is generally not accepted by car designers. On the other hand, when a long turning range is chosen, the wiper rods do not lend themselves to satisfactory manufacture by a corresponding automaton because they differ one from another in their response to subsequent processing. For example the response of long wiper rods tends to vary one from another when subject to forces which cause the wiper rods to yield elastically. Frequently, wiper rods must be "realigned" after painting, since they may have been influenced by stresses associated with the application of heat used during the painting (e.g. stove-enamelling) process.
In contrast thereto, the mentioned FR-A 2 517 609 suggests to transfer the bending function to the connecting head so that a wiper rod can be used which is not bent. This variant, too, is unattractive and its use is not possible in all applications because of the space required by this design. In addition, its manufacturing costs are high.
Consequently, an object is to improve a wiper arm of the type initially referred to such that it can be furnished with the necessary bending and still be attractive inexpensive to manufacture.
A conventional, unbent connecting head can be used with this wiper arm. Further, bending of the wiper rod is not required. Nevertheless, the necessary bending angle is achieved by shifting the bending function to the arm head. Usually, the arm head is long enough to ensure a slight bending, which is hardly perceivable under conventional bending angles. Manufacturing and assembling this arm head is not more difficult than manufacturing a conventional arm head. Also the arm head is as easy to access (for maintenance) as conventional heads. Of course, bending the arm head is effected without step, (i.e. that means continuously from one end to the other). Conventionally, it can be made from a plane sheet metal, and the attachment of the conventional appendages such as the wiper rod and swivel connection with the connecting head is possible using conventional techniques.
Preferably, the bending angle of the arm head is approximately 15.degree.. Thereby, the correct alignment of the wiper blade in relation to the windshield surface is accomplished in the designs found in most late model vehicles.
Another embodiment of the present invention is characterized in that the lateral distance of the lateral legs of the arm head at the end close to the wiper rod is less than the lateral distance of the lateral legs at the end close to the connecting head, that means, the head arm tapers from the connecting head to the wiper rod.
A particularly preferred embodiment of the present invention is characterized in that, at the end of the arm head close to the wiper rod, the two lateral legs are deflected in relation to one another in order to enclose and retain the associated wiper rod end at least in part. First, the loose arm head has a U-shaped cross section quasi over its entire length. After the wiper rod has been inserted into the end of the arm head close to the wiper head, the U-legs are deflected in relation to one another and, as a result, the wiper rod at the arm head is attached. Accordingly, the arm head does not only taper towards the wiper rod, in addition, its height reduces from the connecting head to the wiper rod, when viewed over the length.
An improvement of the present invention is characterized in that each of the lateral legs at the wiper-rod-sided front edge of the arm head, prior to the deflection, encloses with the cross bar an identical angle of, preferably, somewhat more than 90.degree.. The latter provision permits ease of insertion of the wiper rod.
Another second embodiment of the present invention is described. The choice of implementing one of the two embodiments depends on the size of the arm head, the material used and the type of automation used. Also, the design of the tool used to manufacture the arm head can play a decisive role.